The present disclosure relates to a taping machine for attaching an insulation tape to an outer peripheral sealing part of a battery cell.
Among secondary batteries that have been recently increasingly used, square secondary batteries and pouch-type secondary batteries that have a small thickness and can be used for products such as mobile phones are highly demanded in terms of shapes of batteries, and lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries that have merits of high energy density, high discharge voltage, output stability, and the like are highly demanded in terms of materials.
In addition, secondary batteries are also classified according to the configuration of an electrode assembly with a positive electrode/separator/negative electrode structure. Representative electrode assemblies may include: a jelly-roll (wound type) electrode assembly having a structure in which elongated sheet-type positive and negative electrodes are wound while a separator is interposed; a stack-type (stacked) electrode assembly in which a plurality of positive and negative electrodes cut into units each having a predetermined size are sequentially stacked while a separator is interposed; and a stack folding-type electrode assembly having a structure in which bi-cells or full-cells, in each of which predetermined units of positive and negative electrodes are stacked while a separator is interposed, are wound by means of a separation film.
Recently, the pouch-type battery cell, having a structure in which a stack-type or stack/folding-type electrode assemblies are embedded into a pouch-type battery case made of an aluminum laminate sheet, has drawn attention due to low manufacturing costs, a small weight, an easily changeable shape, and the like, and the use thereof is gradually increasing.
FIG. 1 is an exploded perspective view schematically illustrating a general structure of an existing typical pouch-type battery cell.
Referring to FIG. 1, a pouch-type battery cell 10 includes: an electrode assembly 30; electrode taps 40 and 50 extending from the electrode assembly 30; electrode leads 60 and 70 welded to the electrode taps 40 and 50; and a battery case 20 accommodating the electrode assembly 30.
The electrode assembly 30 is a power generating element in which positive and negative electrodes are sequentially stacked while a separator is interposed, and has a stack-type or a stack/folding-type structure. The electrode taps 40 and 50 extend from each of electrode plates of the electrode assembly 30, and the electrode leads 60 and 70 are electrically connected by, for example, welding, to the respective electrode taps 40 and 50 extending from each of the electrode plates of the electrode assembly 30 and have portions exposed outside the battery case 20. In addition, insulating films 80 are attached to a portion of the top and bottom surfaces of the electrode leads 60 and 70 to improve sealing property and ensure electrical insulation state with respect to the battery case 20.
The battery case 20 is formed of an aluminum laminate sheet which is a soft packaging material, provides a space for accommodating the electrode assembly 30, and has a pouch shape as a whole. In the case of the stack-type electrode assembly 30 as illustrated in FIG. 1, an inner upper end of the battery case 20 is spaced apart from the electrode assembly 30 so that a plurality of positive electrode taps 40 and a plurality of negative electrode taps 50 are coupled to the electrode leads 60 and 70 together.
Such a pouch-type battery cell has a limitation in that in a step of accommodating the electrode assembly into the laminate sheet, injecting electrolyte, and sealing through thermal fusion or the like, an inner resin layer of a thermal fusion region (outer peripheral part) protrudes to the outside due to contamination during the injection of electrolyte, excessive fusion phenomenon in the innermost resin layer of the laminate sheet, and/or pressurization, so that a perfect sealing state cannot be maintained even after performing the thermal fusion, moisture easily penetrates into the battery cell, and the electrolyte may leak.
In addition, in the pouch-type battery cell, an insulation breakdown phenomenon may be caused because a metal layer is exposed at an end portion of the laminate sheet which is the battery case, and there is possibility that moisture or the like may penetrate through the thermal fusion portion at the end portion.
Regarding this, there is a well-known technique for improving sealing property together with insulation by attaching an insulation tape to the outer peripheral part of the battery cell.
Conventionally, a battery cell having such a structure was manufactured such that a worker manually removes a release paper of a tape and then attaches the tape in a predetermined shape to the outer periphery of the thermal fusion part of the battery cell.
However, such a method has drawbacks in that a plurality of workers are required, a long process time is consumed due to the manual work, and thus, the manufacturability of the method is low.
This causes a rise in the unit price of the battery cell, and as described above, this is a reason for making mass-production of a high-quality battery cell having improved insulating and sealing properties difficult.
Thus, a technique that can radically solve the above-described limitations is highly demanded.